import numpy as np

a = np.zeros((3,4))   #生成一个三行四列的矩阵,数字为0
print(a)
#输出为
# [[0. 0. 0. 0.]
# [0. 0. 0. 0.]
# [0. 0. 0. 0.]]


a = np.empty((3,4))   #生成一个0的矩阵
print(a)
#输出为
# [[0. 0. 0. 0.]
# [0. 0. 0. 0.]
# [0. 0. 0. 0.]]